Adhesive processes for the attachment of soles to shoe uppers



Oct. 18, 1966 J. M. NARDONE 3,278,959

ADHESIVE PROCESSES FOR THE ATTACHMENT 0F SOLES T0 SHOE UPPERS FiledSept. 22, 1965 78 Inventor JBhnMNar-done By his Afforney a United StatesPatent 3,278,959 ADHESIVE PROCESSES FOR THE ATTACHMENT OF SOLES TO SHOEUPPERS John M. Nardone, Wakefield, Mass, assignor to United ShoeMachinery Corporation, Flemington, N.J., a corporation of New JerseyFiled Sept. 22, 1965, Ser. No. 489,198 7 Claims. (Cl. 12142) Thisapplication is a continuation-in-part of my c0- pending applicationSerial No. 268,167, entitled Adhesive Process for the Attachment ofSoles to Shoe Up pers, filed March 26, 1963.

This invention relates to an improved process for attaching soles toshoe uppers.

Hot melt adhesive sole attaching involves applying thermoplastic (in thesense of heat fusible), synthetic polymeric adhesive on the attachingmarginal surface of a shoe sole and assembling and pressing the solewith the adhesive in molten condition against the heated bottom of ashoe upper. In this process the adhesive may be supplied in moltencondition and the temperature and quantity of adhesive applied may becontrolled to supply at least the amount of sensible heat necessary tomaintain the adhesive in activated, sole bond-ing adhesive condition.Alternatively thermoplastic adhesive on the attaching marginal surfaceof a shoe sole may be brought from solid to molten condition by aheating step prior to assembling of the sole with the shoe upper.

The development of a strong bond by the polymer resin adhesive isdependent in considerable measure on the successful penetration and/ orthorough wetting of the surfaces to be bonded. Because theirregularities in the roughed surface of the outsole and of the bottomof the upper due, for example, to pleating at the toe and to tacks orother holding devices, it has been necessary to use at least a minimumthickness for the ribbon of deposited adhesive and some difficulty hasbeen encountered in the sole attaching pressing operation. That is, themolten adhesive has allowed skidding of the outsole relative to the shoeupper by a lubricating action. Also in the course of pressing, somedifficulty has been encountered due to squeeze out of molten adhesivefrom between the outsole and shoe upper.

It is an object of the present invention to provide a hot melt adhesivesole attaching process in which a strong over-all sole attaching bond issecured with minimum danger of squeeze-out.

To these ends and in accordance with a feature of the present invention,thick deposits of thermoplastic adhesive are laid down in spaced areason the attaching marginal portions of a sole with adjacent areas in theattaching marginal portions having insufiicient adhesive for soleattaching, i.e. either a thin coating or no coating, the areas withinsufficient adhesive being disposed to receive molten adhesive from thethick deposits in subsequent assembly and pressing steps of soleattaching.

Squeeze-out is prevented most effectively if the thick deposits aredisposed inwardly of the outer edges of the attaching margin-a1 portionsof the sole leaving a strip with insuflicient adhesive along the outeredges of the attaching marginal portionsof the sole. In a preferred formthe thick deposits are provided in the form of spaced lines or ridges ofsubstantial thickness and narrow width. The thickness, location andrelative size of the thick deposits of thermoplastic adhesive and of theareas with insuflicient adhesive are arranged to provide a quantity ofadhesive elfective for sole attaching over substantially the entireattaching marginal area. For example, if the desired over-all level ofadhesive for sole attaching were 0.010 inch, the volume of adhesive inthe shoe for areas 3,278,959 Patented Oct. 18, 1966 "ice above thislevel would be adjusted to be at least about equal to the free space upto this level in the areas with insuflicient adhesive.

With the adhesive in at least the thick deposits in molten adhesivecondition from the sensible heat of deposition in molten condition or inmolten condition from a heating step, the sole is pressed against theheated bottom of a shoe upper to force the adhesive into attachingrelation with the shoe upper. The attaching pressure spreads outadhesive from the thick deposits so that adhesive connection is securedbetween substantially all areas of the attaching marginal surface of thesole and the bottom of the shoe upper. The ability of the areas withinsufficient adhesive to accept adhesive reduces the danger of squeezeout, while at the same time the thickness of adhesive in the thickdeposits enables the adhesive to enter into very elfective wettingengagement with the bottom of a shoe upper, but to set up quickly whenspread out by pressure.

The invention will be described further in connection with the attacheddrawings forming part of the disclosure of the present case in which:

FIG. 1 is a diagrammatic angular view with parts broken away of amodified outsole cementer laying down hot molten adhesive on theattaching margin of an outsole;

FIG. 2 is an enlarged angular View of a portion of an outsole partiallyin section with a band of adhesive having thin outer edge areas and withthicker areas spaced from the edges of the band;

FIG. 3 is an enlarged angular view of a portion of an outsole partiallyin section with adhesive strands on the attaching margin;

FIG. 4 is a diagrammatic elevational view showing the heating of thebottom of a shoe upper;

FIG. 5 is a diagrammatic elevational view showing the heating of theadhesive and adjacent areas of attaching margin on the surface of anoutsole;

FIG. 6 is a diagrammatic elevational view partially in section showingthe bonding of an outsole to an upper in a sole attaching press; and

FIG. 7 is an elevational view with parts broken away showing the allover adhesive bonding secured by pressing the outsole against the bottomof a shoe upper.

Successful operation of the present process involves a balance andcontrol of the quantity of molten adhesive deposited and its locationand distribution on the attaching margin of the outsole. Adhesivedeposits of greater thickness are so disposed as to quantity andproximity. to areas with less than sufficient adhesive for soleattaching that adhesive in the thicker areas is able to spread over ontothinner areas under the force of sole attaching pressure to insure thepresence of sole attaching adhesive for a good sole attachingconnection. This distribution of adhesive offers the advantage that thethicker areas, having less surface area per unit volume, retain heatbetter so that they remain in active adhesive condition for periodsallowing greater latitude in manipulation of the outsole and shoe upper.

Best all over connection between the attaching margin of the outsole 10and the bottom of a shoe upper 12 is secured with a disposition ofadhesive as shown in FIGS. 1 and 2 in which the adhesive deposit 14covers substantially the entire attaching margin of the outsoleextending at its outer edge 16 just short of the juncture 18 (see FIG.7) where upper and sole comes together in the completed shoe, and withthin areas 2.0 (see FIG. 2) i.e., areas having less than sufficientadhesive for sole attaching along the outer edge of the attachingmargins. Deposition in the thin areas of only enough adhesive to wet theattaching marginal surface of the sole gives better over-all bond- 3 ingthan is obtained where such areas do not have deposited adhesive. At thesame time where the thicker bodies 22 of adhesive are spaced from theouter edge 16 of the adhesive band any material. squeezed towards theouter edge can be taken up by space. between the sole and the bottom ofa shoe upper 12; It is to be noted that the thin areas 20 of the bandhave effected a wetting of the attaching margin of the sole so thatadhesive from thicker areas 22 does not have to'supply heat to insurefluidity of adhesive for entering into Wetting engagement with the sole.a 7

The deposition of molten adhesive in areas of lessthickness and greaterthickness may involve a variety of patterns, for example, spaced buttonsor mounds, short ridges or a variety of other patterns distributed alongthe length of the attaching margin of the sole. For purposes ofconvenience the process will be described in connection with the patternshown in FIGS. 1 and 2 in which the areas 22 of greater thickness are inthe form of spaced ribs continuous with a thin deposit 20 of adhesivecovering the rest of the attaching margin of the sole and extendinglongitudinally parallel to and spaced from each other and from the outeredge 16 of the band. I

An illustrative procedure to aid in understanding the operation of theinvention isthe process of cement outsole attaching in which a molten,solvent-free thermoplastic adhesive is spread as a band 14 on theattaching margin of an outsole 10 by a modified outsole cementer 24, asshown in FIG. 1. The outsole cementer, 24 comprises a nozzle 26 forapplying and spreading the adhesive, a drive wheel 28 for moving theoutsole 10 at a desired rate past the nozzle 26, and a guide 30 formaintaining the margin of the outsole 10 in desired relation to thenozzle 26. The outer edge 16 of the band 14'of adhesive as applied isjust inside, e.g. up to ,5 inch inside the line of juncture 18 betweensole 10 and upper 12 in the completed shoe. In the device shown, moltencement for the nozzle '26 is supplied from the melting device 32 forhandling a rod or strand 34 of thermoplastic adhesive; but it is to beunderstood that other molten adhesive supplies may be used where thenature of the adhesive permits.

As shown in FIG. 1, the cemeter 24 applies a band 14 extending around atleast the forward portion of the outsole 10'and it may extend around theentire margin of the outsole depending on the shoe constructioninvolved; The deposited band 14 of adhesive may have a thickness of theorder of about 0.002 to about 0.008 inch, in the thinner area 20, andfrom about 0.02 to about 0.05 inch in the thicker areas or ridges 22.The adhesive is applied at a temperature substantially above its meltingpoint to secure good wetting of the sole and preferably is at atemperature sufiiciently high to provide sensible heat for maintainingthe adhesive at least in the thicker areas 22 in molten condition for atime adequate for sole attaching operations. For this type of operation,the temperature should be at least 30 C. and may be 100 C. or more abovethe melting point of the adhesive. With such temperatures and with thecross section of adhesive in the thicker areas 22, as much as 20 secondsmay be available for assembling outsole and upper and pressing themtogether to form a permanent bond.

The thermoplastic adhesive useful for outsole attaching according to thepresent method, involves a special combination of physicalcharacteristics for effective operation. In general, the adhesive mustbe thermoplastic at least to the extent that it does not set up prior tocompletion of the assembly operationsinvolved in the present process.

Resins having molecular weights preferably not over about 50,000 havebeen preferred in order that they may have necessary fluidity forspreading, wetting and penetration. Mixtures of polymeric materialshaving molecular weights above this value, with resins of lowermolecular weight may be compounded to approximate the physicalproperties of the preferred resins for use in the present process. Ithas been found desirable that the adhesive have a melting point (balland ring) of from about C., to about 200 C. and have a relatively widetemperature range, preferably a range of at least 20 C. in which it isvisco-elastic when cooled from molten con dition. The term visco-elasticrefers to a condition in which the adhesive is somewhat rubbery butdeformable and flowable under pressure, in order that it may permitlimited movement, for example, of the outsole 14 relative to an upper-30so that accurate positioning of the outsole 14 relative to the upper 30may be assured even after: the outsole has come in contact. Thetemperature range in which the visco-elastic condition in the preferredad-i hesives occurs may be from about 10 C. to about 60 C. below themelting point of the adhesive; and the adhesive will harden to a strong,tough condition at temperatures at least as high as 50 C. Otherimportant properties are relatively high strength, toughness and atleast limited flexibility at room temperaturein order that the adhesivemay successively withstand the severe stresses encountered in the use ofa shoe.

Synthetic polymer resins which have been found use. ful include thepolyesters from reaction and condensation of one or more dicarboxylicacids, for example, terephthalates, isophthalates, sebacates, azelates,succinates andglycols. Preferred polyesters include condensates of alower alkylene glycol such as ethylene glycol or butylene. glycol withdicarboxylic acids, for example, condensates of 1,4 butane diol withmixed terephthalate and isophthalate components in the molar ratio offrom about 1:1 to about 4:1 and condensates of mixed ethylene glycol and1,4 butane diol and mixtures of these with mixed terephthalate,isophthalate and sebacate or azelate cornponents in percentages of 40%to 60% terephthalate, 20% to 50% isophthalate and 10% to 20% sebacate orazelate. Polyesteramides, for example, adipic polyesteramides in whichthe hydroxy component is 1,6 hexane diol, 1,4 butane diol or ethyleneglycol, stereo-specific catalyzed polymers of vinyl alkyl ethers wherethe alkyl. group has from 1 to 4 carbon atoms, polymers and copolymersof lower alkyl acrylates and methacrylates are also useful.

The outsole 10 is assembled with the band 14 of hot molten adhesive onits attaching margin against the heated sole attaching surface 36 of theshoe upper 12..

The attaching surface 36 of the shoe upper 12 may be heated by disposingthe upper on a rack 38 in spaced relation to a radiant heating unit 40as shown in FIG. 4.

With plastic upper materials, for example, plasticized vinyl chloridepolymers and copolymers, it is desirable that the attaching surface ofthe upper be heated to about to about F., and with leather upperstemperatures of to F are preferred.

The assembled shoe upper 12 and outsole 10 are placed promptly in a soleattaching press 42 (see FIG. 6) and subjected to sole attachingpressure. As pressure is applied to the outsole it is conformed andpressed against the shoe bottom. The molten adhesive in the thickerareas 22 wets the attaching surface 36 of the upper and is spread outonto the thinner areas 20 to improve all over adhesion. Themoltenadhesive will cool and harden quickly and sole attaching pressure maythen be released and the shoe removed from the press 42 within a fewseconds after the sole 10 has been pressed into all over engagement withthe attaching surface 36 of the shoe;

upper 12. V

In an alternativeprocedure the molten adhesive is ap plied to theattaching marginal portion of an outsole 10 1n theform of spaced lines,separated by spaces 46 contammg no adhesive (see FIG. 3) 'but the spaces46:

may also have adhe'sive'to a thickness less than desired for soleattaching. The deposited lines 44 of adhesive where the spaces 46 aresubstantially free from adhesive may be of the order of about 0.025" toabout 0.06", preferably 0.03" to 0.05" in thickness and from 0.025"

to 0.10" in width. It is desirable that the width of the spaces 46 be atleast equal to the thickness of the lines 44 and preferably from 2 to 4times the thickness.

In this alternative procedure, the molten adhesive applied to the ousoleis allowed to cool to form lightly adhering lines or adhesive band whichmay be strippable as self-supporting lines or band. The outsoles 10 maybe stacked substantially directly after application of the adhesivebecause of the rapid solidification of the adhesive.

Completion of this form of the sole attaching process involves heatingof the sole attaching surface 36 of an upper 12 by any suitable means,usually by disposing the upper 12 on a rack 38 spaced from a radiantheating unit 40 as shown in FIG. 4. The outsole 10 is positioned on arack 48 relative to a radiant heating unit 50 so that the radiant heatfalls on the adhesive lines 44 and the surfaces of the outsole 10adjacent the lines 44. The lines 44 of adhesive are softened by theradiant heat with the upper portions of the lines which receive heatmost directly being made more fluid than portions of the lines closer tothe outsole surface. Heat is also absorbed by the outsole materialadjacent the adhesive lines to prepare the outsole surface for permanentadhesive engagement by molten adhesive. It has been found that theadherence of the lines to the outsole surface is important since itholds the adhesive lines in extended condition and does not allow thebeading up as would be caused by surface tension of adhesive merely laidon a surface.

After heating of the sole attaching surface 36 of the shoe upper 12 andradiant heating of the lines of adhesive 44 and portions of the outsole10 adjacent the lines, the outsole 10 is positioned on the bottom 36 ofthe shoe upper 12. The adhesive in the lines 44 although somewhatrubbery in heated condition, has a visco-elastic nature which allowssome sliding of the outsole 10 relative to the shoe upper 12; but thesliding is limited in extent.

After positioning of the outsole on the bottom of the shoe upper, theassembled shoe upper 12 and outsole 10 are placed in a sole attachingpress 42 (see FIG. 6) and subjected to sole attaching pressure.Surprisingly, notwithstanding the amount of time which is available forassembling of the outsole and upper, pressure in the sole attachingpress 42 may be released in a matter of only a few seconds. The abilityof the adhesive to hold the outsole 10 firmly on the shoe upper 12 afterso short a time is due in some measure to the fact that the deeplyheated outsole portions permit excellent penetration of the moltenadhesive, i.e., do not chill penetrating portions of the adhesive toconstitute a block against further penetration. This excellentpenetration and/or wetting of the outsole and shoe upper by the adhesivereduce the thickness of the adhesive between outsole and upper and whensole attaching pressure is applied create a geometry between the outsoleand shoe upper in which the adhesive may function most effectively.

The process described is applicable both to leather outsoles and tonatural or synthetic rubber outsole materials. With natural of syntheticrubber outsole materials in many cases it is desirable to provide aprimer coat on the attaching surface of the outsole to improve the unionbetween the thermoplastic adhesive and the outsole. Suitable prirnercompositions include a solution of chlorinated rubber in a volatileorganic solvent or a solution of a relatively stable polyisocyanate, forexample, a polyarylene polyisocyanate commercialy available as PAPI.

The following examples are given to aid in understanding the invention.It is to be understood that the invention is not restricted to theparticular materials, proportions or procedural conditions employed inthe examples.

Example I A polyester was prepared by the reaction of 1,4 butane diolwith dimethyl terephthalate, isophthalic acid and azelaic acid, thesethree materials being used in molar ratios of 4.4:4.4:1.3. Thecondensation was carried out to form a resinous adhesive material havinga melting point of about 120 C. (ball and ring). This material wasformed into a rod of about A thickness and sup plied to a melting andapplying device which deposited it at a temperature of 245 C. as amolten adhesive band on the marginal attaching surface of an outsole.The band was about /2" wide, about 0.003 to about 0.004 in thickness inits thinner areas and with spaced parallel ribs 0.030" to 0.035" inthickness spaced about /s" apart and with the outer ribs about from theedge of the band.

The bottom of a fabric-backed polyvinyl chloride plastic shoe upper wasexposed to radiant heat for about four seconds to raise the temperatureof the attaching surface of the shoe upper to about 120 to 130 F. andthe outsole was spotted against this upper directly after deposition ofadhesive on the outsole and the assembly placed in a sole attachingpress equipped with a concave surfaced press pad. Pressure was appliedto the extent of about 200 lbs. per sq. inch on the assembly and after 8seconds the pressure was removed. On examination it was found that thesole was strongly attached to the shoe upper and that there had been nosqueeze out of adhesive.

Example 11 The procedure of Exam-pile I was repeated but 15 seconds wereallowed to elapse between the application of adhesive to the outside andthe spotting of the outsole on the upper and the application ofattaching pressure. In

this also the sole was strongly attached to the shoe upper and there wasno squeeze out of adhesive.

Example Ill The procedure of Example I was repeated using a six ironleather outsole. In this case also there was no squeeze out of adhesiveand the sole was strongly and uniformly bonded to the shoe upper.

Example IV Example V A polyester was prepared by the reaction andcondensation of 1,4 butane diol and equimolar proportions of dimethylterephthalate and isophtha-lic acid. Condensation was carried out toform aresinous material having a melting point of about 142 C. (ball andring). This resin was formed into a flexible rod about inch in thicknessand the rod was fed to a melting device di posed to provide moltenadhesive to an outsole cementer. The nozzle of the cementer was providedwith four orifices for extrusion of the molten resin adhesive, eachorifice being 0.030 inch in diameter. The orifices were spaced about0.10 inch apart. 'Ilhe melting device and cemeuter were adjusted todeliver molten resinous material through the nozzle to the surface of aleather outsole at a tempetrat-ure of 350 F. The lines of resindeposited on the outsole solidified promptly after deposition and were 7found to have a thickness of about .025 and a width of about .040 inch.

The leather outsole was disposed with the surface oa rying the lines ofresin adhesive toward a radiant heat source for 15 seconds. The radiantheat raised the surfaoe temperature of the leather to about 150 to 175F.; and raised the temperature of the lines of adhesive to an extentthat the resin became fluid and wet the surf-ace of the leather.

At the same time the bottom of a shoe upper was exposed to radiant heatto raise the temperature of the attaching surface of the shoe upper toabout to about F. The outsole was then spotted on the upper and theassembly placed in a sole attaching press. Pressure was applied to theextent of 200 to 225 lbs. gauge pressure on the assembly, and after tenseconds the pressure was removed. On examination it was found that thesole was strongly attached to the shoe upper, that the edges of the solewere very tight to the upper and that there had been no squeeze-out ofadhesive.

Example VI A polyester was prepared by the reaction and condencation ofethylene glycol with a mixture comprising in terms of mol percentages60% of dimethyll terephthalate, 20% isophthalic acid and 20% sebacicacid. Condensation was carried out to the extent of providing a meltingpoint of 170 C. (ring and bail). This resin was formed into a rod andused for attaching leather soles to shoe uppers, using the procedure andconditions set forth in Example V but delivering the molten resinousmaterial at a temperature of about 375 F. The sole was found to bestrongly and tightly attached to the shoe upper.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent of the United States is:

1. The process of permanently attaching a shoe sole and a bottom of ashoe upper which comprises depositing hot molten substantiallysolvent-tree thermoplastic synthetic polymeric resin adhesive over theattaching marginal surfiace of said sole, areas of said attaching margindisposed nearest the outer edge of said sole having less than sufficientadhesive for sole attaching and being adapted and arranged to acceptadhesive forced from other areas of said attaching margin to resistsqueeze out, the adhesive in said other areas being substantiallythicker than in the first mentioned areas to provide a total quantity ofadhesive in said attaching margin sufiicient for adhesive connectionbetween substantially the entire attaching marginal surface of said soleand adjacent areas of a shoe bottom, heating the bottom of the shoeupper, assembling said sole with its adhesive against said heated bottomwith the adhesive in at least said areas of greater thickness in moltenadhesive condition, exerting pressure to fiorce the adhesive intopermanent attaching relation with the heated surfiace of the shoe bottomand cooling the adhesive to establish rapid-1y a strong union of thesole and the shoe.

2. The process of permanently attaching a shoe sole and a bottom of ashoe upper as defined in claim 1 in which said other areas havinggreater thickness of adhesive are spaced bodies of adhesive continuouswith adhesive on the first-mentioned areas of the attaching margin, saidbodies being of such size and so located along said marginal attachingsurfiace as to supply adhesive to areas with less than sufficientadhesive for sole attaching.

3. The process of permanently attaching a shoe sole and a bottom of ashoe upper as defined in claim 2 in which said spaced bodies areparallel ridges of adhesive 8 extending the length of said marginalattaching surfaces and being of such size as to supply adhesive to areaswith less than sufiicien-t adhesive tor sole attaching.

4. The process of permanently attaching a shoe sole and a bottom of ashoe upper which comprises depositing a band of hot molten substantiallysolvent-tree thermoplastic synthetic polymeric resin adhesive oversubstantially the entire attaching marginal surface of said sole, astrip of said band extending the length of said band and disposedadjacent the edge of said band nearest the outer edge of said solehaving 'less than sufiicient adhesive .for sole attaching and 'beingadapted and arranged to accept adhesive forced from other areas of saidband to resist squeeze out, the adhesive in said other areas beingsubstantially thicker than in said strip to provide a total quantity ofadhesive in said band sufficien t for sole attaching adhesive connectionbetween substantially the entire attaching marginal surface of said soleand adjacent areas of a shoe bottom, heating the bottom of the shoeupper,

asemb-ling said sole with its hand of adhesive against said heatedbottom with the adhesive in at least said areas of greater thickness inmolten adhesive condition, exerting pressure to force the adhesive intopermanent attaching relation with the heated surface of the shoe bottomand cooling the adhesive to establish rapidly a strong union of the soleand the shoe.

5. The process of permanently attaching a shoe sole and a bottom of ashoe upper as defined in claim 4 in which said other areas havinggreater thickness of adhesive are spaced parallelridges of adhesivecontinuous with, adhesive on said stnip, extending the length of saidmare ginal attaching surface and being of such size as to supplyadhesive to areas with less than sufiicient adhesive for sole attaching.

6. The process of permanently attaching a shoe sole and a bottom of ashoe upper as defined in claim 5. in which the adhesive in at least saidareas of greater thickness is retained in molten adhesive condition forsole at References Cited by the Examiner UNITED STATES PATENTS 2,385,5239/1945 Marasco 12 142 2,648,078 8/1953 Eppler 12-55 3,021,543 2/1962Crowley 12 142 3,056,984 10/1962 Snitzer 12-142 3,168,754 2/1965Rossitto 12-142 JORDAN FRANKLIN, Primary Examiner.

PATRICK D. LAWSON, Examiner.

1. THE PROCESS OF PERMANENTLY ATTACHING A SHOE SOLE AND A BOTTOM OF ASHOE UPPER WHICH COMPRISES DEPOSITING HOT MOLTEN SUBSTANTIALLYSOLVENT-FREE THERMOPLASTIC SYNTHETIC POLYMERIC RESIN ADHERSIVE OVER THEATTACHING MARGINAL SURFACE OF SAID SOLE, AREAS OF SAID ATTACHING MARGAINDISPOSED NEAREST THE OUTER EDGE OF SAID SOLE HAVING LESS THANNSUFFICIENT ADHESIVE FOR SOLE ATTACHING AND BEING ADAPTED AND ARRANGED TOACCEPT ADHESIVE FORCE FORM OTHER AREAS OF SAID ATTACHING MARGIN TORESIST SQUEEZE OUT THE ADHESIVE IN SAID OTHER AREAS BEING SUBSTANTIALLYTHICKER THAN IN THE FIRST MENTIONED AREAS TO PROVIDE A TOTAL QUANTITY OFADHESIVE IN SAID ATTACHING MARGIN SUFFICIENT FOR